Inflight entertainment (IFE) systems have evolved significantly over the last 25 years. Prior to 1978, IFE systems consisted of audio-only systems. In 1978, Bell and Howell (Avicom Division) introduced a group viewing video system based on VHS tapes. In 1988, Airvision introduced the first in-seat video system allowing passengers to choose between several channels of broadcast video. In 1997, Swissair installed the first interactive video on demand (VOD) system. Currently, several IFE systems provide VOD with full digital video disc-like controls.
Some airlines require that each passenger have access to a flight attendant call button upon departure. Flight attendant call buttons are part of the passenger safety system which airlines may include in their minimum operating equipment list filed with the Federal Aviation Administration (FAA). On narrow body aircraft, flight attendant call buttons are generally mounted overhead in the cabin ceiling and are completely independent of the IFE system. On wide body aircraft, however, the cabin ceiling is typically too high for a passenger to reach. Therefore, on wide body aircraft, flight attendant call buttons are often incorporated into the IFE system as part of passenger control units mounted in passenger seats.
A consequence of integrating flight attendant call buttons with the IFE system on wide body aircraft is that flight attendant call buttons rely on IFE system power. Thus, if an IFE system power supply unit fails, the flight attendant call button at every passenger seat that relies on that power supply unit will not work. In that event, the cabin crew may relocate the impacted passengers to unused seats or, in the event an insufficient number of seats are available, may ask for volunteers to move to a later flight for some reward.
Since relocation and removal of passengers is inconvenient, time consuming and costly, on wide body aircraft a power supply unit is typically distributed to every triple seat group to minimize the impact of failure of a single power supply unit. FIG. 1 illustrates conventional power distribution for an IFE system on a wide body aircraft 100. A power supply unit is dedicated to each triple seat group. For example, triple seat group 110 consists of three seats 111A, 111B, 111C mounted to a common frame. A power supply unit 112 is dedicated to triple seat group 110. Power supply unit 112 converts aircraft power to local power and distributes local power to seats 111A, 111B, 111C via a power cable 113 for use by the IFE electronics at seats 111A, 111B, 111C. If power supply unit 112 fails, the cabin crew may relocate the three impacted passengers to unused seats, or if an insufficient number of seats is available, may ask for volunteers to move to another flight for some reward. Still, as long as the other triple seat group power supply units remain operative, the inconvenience, delay and cost caused by this failure is limited.
Nonetheless, the conventional wide body aircraft power provisioning shown in FIG. 1 has certain drawbacks. First, dedicating a power supply unit to each triple seat group is very costly. For example, 60 power supply units are required in wide body aircraft 100 shown in FIG. 1. Second, even though the disruption resulting from failure of a single power supply unit is limited, as many as three passengers are still impacted by each such failure.
In a narrow body aircraft in which flight attendant call buttons are decoupled from the IFE system, IFE systems with more efficient power distribution have been deployed. FIG. 2 illustrates a conventional approach to power provisioning for an IFE system on a narrow body aircraft 200. Triple seat groups are organized into power zones each consisting of five triple seat groups. In all, there are 12 power zones (labeled A-L). Power zone G is shown in greater detail to better illustrate power provisioning. A single power supply unit 212 provides power for the power zone, which consists of five triple seat groups each having three seats (e.g., 211A, 211B, 211C). Power is distributed both between triple seat groups and to individual seats through power cable 213. By dedicating one power supply unit for 15 seats, the number of power supply units deployed on aircraft 200 is reduced from 60 to 12 relative to the wide body aircraft shown in FIG. 1, significantly reducing power supply costs for the IFE system. However, if this power distribution system were deployed on a wide body aircraft where flight attendant call buttons are integral with the IFE system, failure of a single power supply unit could require relocating as many as 15 passengers or finding up to 15 volunteers to switch to another flight, causing a major operational disruption.